Composite substrate and production method therefor

Abstract

Provided are a composite substrate in which a wafer to be bonded has a sufficiently small surface roughness and which can be prevented from causing film peeling, and a method for producing the composite substrate. The composite substrate 40 of the present invention has a silicon wafer 10 , an interlayer 11 , and a single-crystal silicon thin film or oxide single-crystal thin film 20 a stacked in the order listed and has a damaged layer 12 a in a portion of the silicon wafer 10 on the side of the interlayer 11.

The invention claimed is: 
     
       1. A method for producing a composite substrate having a silicon wafer, an interlayer, and an oxide single-crystal thin film stacked in the order listed, comprising the steps of:
 forming the interlayer on a surface of the silicon wafer; 
 subjecting a side of the interlayer of the silicon wafer to ion implantation treatment and then to thermal treatment at a temperature of 400° C. to 600° C. to form a damaged layer in a portion of the silicon wafer on the side of the interlayer; 
 bonding the silicon wafer and an oxide single-crystal wafer to each other with the interlayer therebetween to obtain a laminate; and 
 thinning the oxide single-crystal wafer of the laminate into the oxide crystal thin film, 
 wherein ion species to be implanted by the ion implantation treatment are hydrogen atom ions (H + ) at a dose between 2.5×10 16  and 5.0×10 16  atoms/cm 2  or hydrogen molecule ions (H 2   + ) at a dose between 1.25×10 16  and 2.5×10 16  atoms/cm 2 . 
 
     
     
       2. The method for producing a composite substrate according to  claim 1 , wherein the interlayer comprises SiO 2 , SiON, SIN, Al 2 O 3 , TiO 2 , Ta 2 O 5 , Nb 2 O 5 , Y 2 O 3 , or ZrO 2 . 
     
     
       3. The method for producing a composite substrate according to  claim 1 , wherein the interlayer is formed by thermally oxidizing the silicon wafer. 
     
     
       4. The method for producing a composite substrate according to  claim 1 , wherein the interlayer is formed by a chemical vapor deposition method (CVD method) or a physical vapor deposition method (PVD method). 
     
     
       5. The method for producing a composite substrate according to  claim 1 , wherein the oxide single-crystal wafer of the laminate is thinned by grinding or polishing, or a combination thereof. 
     
     
       6. The method for producing a composite substrate according to  claim 1 , further comprising a step of subjecting the surface of the oxide single-crystal wafer to be bonded to ion implantation treatment to form an ion implantation layer in the oxide single-crystal wafer,
 wherein the oxide single-crystal wafer of the laminate is thinned by leaving the ion implantation layer as an oxide single-crystal thin film and releasing the remaining portion of the oxide single-crystal wafer from the laminate.